China has said it was alarmed over Philippines' move to lease five aircraft from Japan and deploy them for surveillance sorties over the disputed South China Sea.
A Chinese foreign ministry spokesman hit out at Japan over the deal saying Tokyo was not a party to South China Sea dispute.
The Chinese reaction came after Philippines President Aquino announced the decision to lease five TC-90 training aircraft from Japan to conduct surveillance flights over its maritime territory claimed by China.
"If the Philippines' actions are to challenge China's sovereignty and security interests, China is resolutely opposed," foreign ministry spokesperson Hong Lei said, according to Reuters.
"I also want to point out that Japan is not a party to the South China Sea issue and we are on high guard against its moves. We demand that Japan speak and act cautiously and not do anything to harm regional peace and stability," Hong added.
While China lays claim to the whole of South China Sea, Philippines, Brunei, Malaysia, Taiwan and Vietnam also have overlapping claims.
Last week Philippine local media had reported that China took over a disputed Philippine atoll in the South China Sea and stationed up to five ships around the fishing ground.
The Quirino or Jackson Atoll, a traditional fishing ground for fishermen from Palawan, was effectively in Chinese control, the PhilStar newspaper had reported.
The Philippines military confirmed they got reports about the presence of Chinese ships in the area.
China and the Philippines are waging a legal battle over territorial disputes in the South China Sea. The dispute is now before an arbitration court in The Hague.
In February, Chinese vessels confronted Philippine Navy's logistic ship BRP Laguna near Hasa-Hasa Shoal, another Filipino fishing ground.
In 2012, China and the Philippines faced off against each other in a tense maritime stand-off over Panatag (Scarborough) Shoal, which lies 100 km from the cost of Philippines and 500 km away from the cost of China's southern Hainan.
The Chinese then took control of the Shoal and forced the Philippines to release Chinese poachers who had been arrested from the area. The Chinese never left the shoal since then.